Electric resistance welding



Dec. 15, 1925- 1,566,208

c. A. HADLEY A ELECTRIC RESISTANCE WELDING Filed July 8, 1924 P Sheets-Sheet 1 Aryan r01? a 4 fiel Dec. 1, 1925' C. A. HADLEY ELECTRIC RESISTANCE WELDING Filed July 8, 1924 2- Sheets-Sheet ITTUK/Vf) uzc 25 53 uzc 3380 on Patented Dec. 15, 1925.

UNITED STATES PATENT oFFIcE.

CECIL ALLARTON HADLEY, OF INVERNESS, SCOTLAND.

ELECTRIC RESISTANCE WELDING.

' Application filed July 8, 1924. Serial No. 724,901.

To all whom. it may concern Be it known that I, Cnorn ALLAR'roN HAD- LEY, a; British subject, of Island Bank Road, Inverness, Scotland, North Britain, have invented certain new and useful Improvements in Electric Resistance Welding, of which the following is a s ecification.

This invention re ates to electric welding and has for its object the provision of improved means whereby the current may be modulated during the welding operation.

In processes of electric resistance welding and more particularly in the process known as seamor line welding it is well known that it is desirable to interrupt the current supply which is used for heating the parts to be welded or. brazed together,.the interruption of the current being dependent upon the linear speed of welding, the thickness of the material which is being operated upon, and the area of the surface of the rollers or other electrodes which may be used to conduct the heating current to the parts to 'narnic or interference beat principle based pound, alternatinghcurrent. is supplied to the t is com un current being obtained on the ph sical'laws of superimposed waves.

Acoordmg' to the present invention a comalternating y superimposing alternating currents from a number of welding means,

sources of suppl For this purpose a number of single p ase alternators, which are identical in construction, are preferably employed as the sources of supply, the current from these sources of supply being passed throu h primary windings of one or more trans ormers of which the secondary windings are in series so that the various currents will be superposed in the circuit which includes the secondary windings.

In order that the invention may be clearly understood it will now be described'by way of. example with reference to the accompanying drawings, wherein:

Fig. 1 shows an arrangement wherein two heterodyne transformers are arranged for the simultaneous operation of two welding machines. t

Fig. 2 shows a diagram of the current curves. I

In the drawing, one alternator-A is connected to the primary winding 0 of a static transformer 6, while the second alternator B is connected to the primary winding 0 of asecond static transformer d. The transformers b and d are of the same constructions and the secondary windings e, f, of the. said transformers are identical with each other and with the primary windings a andc, and are arranged in series with the primary winding 9 of welding transformer h, the secondary winding of-wh-ich is indicated at 70.

As two welding machines are -contemplated, there is provided for the second welding machine a second transformer h, and the primary winding 9' of this transformer is arranged in series with additional primary windings e, f on the transformers b and d. The secondary winding ofthe transformer h is indicated at k; The secondary windings e, f are identical with each other and with the secondary windings e, f; In this arrangement the windings e, f'

and e, f respectively are arranged in opposition so that while, for example, the transformer his supplying its maximum current, the transformer k is supplying its minimum current, and vice versa.

The operation of the arrangements above described employing two single phase alter- .nators A, B of identical construction will now be described with reference to the diagram Fig. 2.

The alternator A is driven at a' speed to produce an alternating current having a frequency 7, cycles per second at a voltage -V The alternator B, however, may be driven at any'desired speed so that its frequency 7, may be equal to any value between :20 to f, a whilst its voltage is reguldted so that it will always be substantially eqlpal to the voltage V ofthe alternatorA. T

e resultant obtained by su erposing the two alternating currents is indicated by the curve f, in Fig. 2.

Now assum ng that both alternators are being driven at the same speed and are running in phase, the frequencies .f, and f, will be equal. The voltages V and V will also be equal in value and magnitude as long as the alternators are driven in synchronism. Under these circumstances the current flowing through the welding circuit will be equal'to the voltage V V, divided by the impedance of' this circuit. a

If the connections of one of the secondary windings to the welding circuitwere re-' versed the voltage induced in this secondary winding would be equal to the voltage in the other secondary. winding, but in the opposite direction, so that no current would flow in the welding circuit. In other words,

' the voltage in the welding circuit. would be V V, 0, so that no currentflows in said circuit. I Y

Referring again to the first method of connections and assuming that the speed of alternator B is increased'so that its frealthough the mean values of the separate voltagesV and remain constant.

By superposing the two alternating currents the period of cooling and welding durmg each cycle will be substantially as indicated by the curve B in Fig. 2, 70% of each cyclebein the period of 30% the perio of cooling.

It may be mentioned in general thatthe ower input to the primary of each transormer varies in proportion to the value of the supply voltage. A considerabledifierence between the two voltages does not appear to affect its heterodynamic effect in welding and the welding circuit, but the power factor is adversely affected and for thisreason it is usual to employ voltages of substantially equal value. I a

- In some cases, however, it may be desirable to use unequal voltages, as, for example, where one supply is taken from an outside.

source and the second supply has to be generated by "an auxiliary I lant such as 'a motor-driven alternator. such a case. it

' is obvious that /it is desirable to make the auxiliary plant as small as possible and this may be done by suitably arranging the respective voltages;

As a practical example of the application of the invention to spot welding with a our- 'rent varying in intensity with a periodicity of two per second, an electrical Suppl;

of say 50- and'48 cycles per second wonl be passed through the two primary of a two-phasetransformer so as 11613170:

duce' 2- cycles per second f-in the external .circuit of: the two secondary-windbeing in ng, one

be fed through'the machine at a speed of 5 feet per minute, that is I per second, and with the above periodicity 2' s 0t welds would be produced per inch. 0 form a continuous spot weld the periodicity'would either be increased or the s eed of feed reduced so that one spot wel would overlap the preceding one, the speed of feed or penodicity being adjusted according to the nature of the weld to be produced It will thus be seen that by the use of awelding system according to the present invention it is possible at will to obtain a wide range in the time factor in a simple manner, whilst the welding current-is modulated or fluctuated without the necessity of breaking the continuity of the circuit.

What I claim is 1. An electric resistance welding system plurality of pr mary windings, one on each of. said transformers, and a plurality of sources of supply of alternating current connected one to each primary winding,

a plurality of sets ofsecondary windings on the transformers with the windings of each. set arranged in series, the winding of. the re ective setsv on one transformer e relatively same direction and the windings of the respective sets on the other transformer being in the relatively opposite direction, and a plurality of welding means each including a winding connected to one of the sets of secondary windings.

2. An electric resistance welding system comprising a plurality of transformers, a

plurality of primary windings, one on each of said transformers, and a plurality of sources of supply of alternating current connected one to each primary winding, a plurality. of sets of secondary windings on the transformers with the windings of each set arranged in series, the winding of'the r ectivesets on one transformer 'in t e relatively same direc tion and-the. winding of the respective sets on the other transformer being in the relativel "opposite direction, and a plurality of we means each including-a windof such secondary windin 5 ing opposed to the second set of sucli secondary windings, whereby when one welding .means is receiving maximum current the other is receiving minimumcurrent.

nected one to eachfprimary winding, a plusources of supplyof ternating' current com be- I rality of-sets of secondary windings on the 4 transformers with the windings, of each set arranged in series, the1 winding of the reformer bemg motion and a pluralit of weldln means each including a winding connecte to one of the sets of secondary windin in series.

4. An electric resistance wel ing system comprising a plurality of transformers, a plurality of primary windings, one on each of I said transformers, and a plurality of sources of supply of alternating current connected one to each primary winding, a plurality of sets of secondary windin on thetransformers with the windings 0 each 'set arranged in series, the winding of the respective sets on one transformer be in the relatively same direction and the windings of the respective sets on the other transformer being in the relatively opposite direction and a plurality of weldm means each including afwinding connecte to one.

of the sets of secondar windin s in series, beingone set of such secon ary win gs opposed to the second set of such secondary windings, whereby when one welding means is receiving maximum current the other is receiving minimum current.

- In testimony whereof-I have signed my name to this specification. I

CECIL ALLARTON HADLEY, 

